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VulnerabilityPublished Updated

CVE-2025-21970: Linux kernel · net/mlx5: Bridge, fix the crash caused by LAG state check

Affects Linux kernelSource GCVE Database

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Not known to be exploited · CVSS 7.8 High · fixed in 5.15.0-1086.93~20.04.1 : patch Linux kernel soon.

Data as of 12 Nov 2026, 19:27 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 5.15.0-1086.93~20.04.1, 5.15.0-1091.100~20.04.1, 5.15.0-1085.94~20.04.1 +64
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 Apr 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 12 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-84.84
Fixed in
  • 6.8.0-84.84
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1039.41
Fixed in
  • 6.8.0-1039.41
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1038.44
Fixed in
  • 6.8.0-1038.44
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threatsAffected
  • <6.11.0-1018.18~24.04.1
Fixed in
  • 6.11.0-1018.18~24.04.1
Ubuntu 24.04 LTSlinux-azure-nvidiapkg:deb/ubuntu/linux-azure-nvidia?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1025.27
Fixed in
  • 6.8.0-1025.27
Ubuntu 24.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1040.42
Fixed in
  • 6.8.0-1040.42

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available and has been released in multiple Linux kernel versions including 5.15.0-1039.39 and later in the 5.15 series. Users should apply the official Linux kernel updates provided by their distribution and reboot the system to activate the fix. No additional mitigations are required beyond applying the official patch.

Description

CVE-2025-21970 is a vulnerability in the Linux kernel's mlx5 network driver related to bridge and Link Aggregation Group (LAG) state checks. The flaw causes a kernel crash when removing a LAG device from a bridge due to improper handling of offloaded entries and stale bridge forwarding database (FDB) entries. This leads to a use-after-free condition where the kernel accesses a destroyed network device, resulting in a crash. The issue has been fixed in multiple Linux kernel versions.

References

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